Another reported mentally unbalanced shooter was the guy who shot at Congreswoman Gifford:
http://abcnews.go.com/Politics/rep-gabrielle-giffords-shot-grocery-store-event/story?id=12571452
From the clip:
“...”We are not convinced that [the gunman in custody] acted alone, there is some reason to believe he came to this location with another individual, and that individual is involved,” Pima County Sheriff Clarence Dupnik said.
Police said a suspect was taken into custody, and Dupnik described the alleged shooter as mentally unstable. Though the sheriff did not name the suspect, he was identified by multiple law enforcement sources as Jared Lee Loughner, 22....”